The present invention relates to alignment and/or stabilizing of the spinal vertebrae. More specifically, the present invention relates to a polyaxial spinal stabilizer and/or alignment system that effectively transfers the load from the vertebrae to the stabilizer using structure that facilitates surgical implantation of the system.
Stabilization and/or alignment of the spinal column is indicated for treatment of many pathologies including trauma, tumor, infection, degenerative spine disease, congenital, iatrogenic spinal instability, spondylolysis/spondylolisthesis, pseudarthrosis, kyphosis, scoliosis, and/or other spinal deformity. A number of stabilizers for treating such pathologies that utilize “hook and rod” components are disclosed in the scientific and patent literature and are available from such vendors as Sofamor-Danek, Osteonics, and others. Such stabilizers utilize screws that are driven into the bodies of adjacent vertebrae, typically in the pedicular region of the vertebral body, and rods that are secured to two, three, or more screws on adjacent segments using hooks that are either formed on or attached to the heads of the screws to stabilize and/or align the vertebrae.
A problem that arises during surgical implantation of such systems involves attachment of the screw to the rod. Depending upon the location on the spine, size of the vertebrae, pathology, and other factors unique to the patient, the screw heads extend at different angles and heights relative to the longitudinal axis of the spine even on adjacent vertebrae. For this reason, it can be difficult for the surgeon to attach the rod or plate to the screws, particularly when the patient suffers from spinal deformity. When a hook and rod system is used to stabilize the spine, the rod can be bent before it is attached to the screw, but when utilized to correct spinal deformity, the rod must be brought to the screw heads such that the connection between the screws and the rod must sometimes be accomplished using brute force. Of course the plate of a plating system cannot be formed or bent to align to the screws with the result that plating systems cannot be used in certain patients and/or for treatment of certain pathologies. In the case of a rod system in which the rod is approximated to the screw heads, the surgeon is working in a surgical stage populated with nerves and other tissues to which the application of force is anathemic. For these and other reasons, there is a need for improvement in such instrumentation, and it is an object of the present invention to provide such improvements.
Another object of the present invention is to provide an apparatus for use in aligning and/or stabilizing the spinal column that reduces the likelihood of traumatic injury to the spinal cord during surgery.
Similarly, in large part because of the difficult geometry caused by the different angles and heights of the pedicular screws, the transfer of the load that is normally carried by the spinal column to the stabilizer through the connection between rod and screw is problematical. Not only must this connection effectively transfer load from vertebrae to spinal stabilizer, but the transfer must be accomplished at any of a plurality of angles between pedicular screws and stabilizer. Several prior art devices appear to address this problem, an example being the pedicular screw and hook believed to be marketed under the trademark ISOBAR by Scient'x (Maitland, Fla., www.scientxusa.com). However, the structure of this prior art device does not facilitate attachment of the rod to the hook when pedicular screws do not line up and/or extend to different heights. It is therefore also an object of the present invention to provide an apparatus and method for effectively transferring load from the spinal column to a spinal stabilizer regardless of the angle and height of the heads of the pedicular screws that anchor the stabilizer to the patient's spine.
It is also an object of the present invention to provide an apparatus and method that facilitates attachment of a rod or plate to a spinal stabilizer by enabling the rod or plate of the spinal stabilizer to be incrementally advanced, or re-positioned, until the rod or plate is positioned so as to allow attachment to the pedicular screws with minimal danger to the nerves and other sensitive tissues within the surgical stage.
There is also a need for instrumentation for use in surgical treatment of spinal deformity and pathology that, because of the ability to incrementally advance the rod or plate to the screw head and to securely lock the rod or plate to the screw head, can be used to conform the rod or plate to the individual patient and to the geometry and configuration of the patient's anatomy, and it is an object of the present invention to provide apparatus and methods meeting that need.
There is also a need for instrumentation that is adaptable for use with both a hook and rod spinal stabilizer and a plating system as needed for stabilization of the patient and/or for alignment of the spine.
There is also a need for instrumentation for use in surgical treatment of spinal deformity and pathology that minimizes surgical trauma and it is also an object of the present invention to provide apparatus and methods meeting that need.
Another object of the present invention to provide instrumentation for use in aligning the spinal column having a construction that reduces the so-called “fiddle factor” involved in the surgery, shortening the duration of the surgical procedure.
It is also an object of the present invention to provide an apparatus in which the rod or plate of a spinal stabilizer is locked against movement relative to the pedicle screw regardless of the angle between the rod or plate and the screw.
It is also an object of the present invention to provide a washer for a spinal stabilizer, particularly a spinal stabilizer that comprises a rod, that is capable of providing a secure connection between the rod and a pedicle screw to which the washer is mounted at any angle relative to the rod.
Another object of the present invention is to provide a cap for receiving a pedicular screw and either the rod or the plate of a spinal stabilizer or alignment device comprising a base having (1) a bore therethrough for receiving the head of the pedicular screw, (2) a threaded post or riser, the bore and the post being offset from each other, and (3) a surface formed thereon adapted for engaging either the rod or the plate of the spinal stabilizer, relative movement of the pedicular screw, base, and the rod or plate being resisted when a nut is tightened on the threaded post.
Other objects, and the many advantages of the present invention; will be made clear to those skilled in the art in the following detailed description of several preferred embodiments of the present invention and the drawings appended hereto. Those skilled in the art will recognize, however, that the embodiments of the invention described herein are only examples provided for the purpose of describing the making and using of the present invention and that they are not the only embodiments of spinal stabilizers that are constructed in accordance with the teachings of the present invention.